Improvement in dental drills



. tapering or beveled shank of such tool.

UNITED STATES vPATENT OFFICE.

JAMES `B. MORRISON, OF BROOKLYN, ASSIGNOR TO JOHNSTON BROS., OF NEW YORK CITY, N. Y.

IMPROVEMENT IN DENTAL DRILLS.

Specification forming part of Letters Patent No. 147,959, dated February 24, 1874; application filed February 6, 1874.

To all whom t may concern Be it known that I, JAMES B. MORRISON, of the city of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Dental Drills; and I hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawing which forms part of this specification.

This invention relates particularly to the construction of the shanks of the tools commonly called burrs and drills, which are used in a dental engine to operate on the teeth while in the mouth, as well as to the formationof a peculiar-shaped tool-socket in that portion of the rotary shaft of the engine, which is wholly or partially enveloped in a sleeve which constitutes part of the hand-piece, so called, which latter enablesthe dentist to grasp the same near the operative end of the tool without interfering withthe rotation of either shaft v or tool, and also affording a bearing to the latter near its operative end, and also enablingv the dentist to guide and control the tool steadily and accurately.

One of the methods of constructing these burrs or drills and adapting the same to the hand-piece of a dental engine has been to provide the shank of the tool with one or more flat or plain inclined surfaces, and also to provide, in the end of the rotating shaft, a socket of corresponding shape, in which to insert the In this case it is obvious that the tool is retained in its socket merely by friction, and hence such tool so held is very apt to drop out, much to the annoyance of the dentist and his patient. Another method has been to provide the end of the tool with a screw-thread, and the end of the shaft with a screw-socket but this con struc'- tion is objectionable, because it properly secures the tool only when rotating in one direction. Another method has been to provide a tool with a shank having one or more squared or plain surfaces entering a corresponding socket in the end of the rotating shaft, and to apply to the hand-piece carrying such tool, or to the shaft, a spring-catch the nose of which engages with the tool in such manner as to hold it securely in its socket, and, at the same time, in

no respect interfere with the rotation of either shaft or tool. In such case the manipulation of the spring-catch was necessary to release the tool.

rIhe object of the present invention is to provide a means for securely holding the tool in its socket and permit of its removal at pleas ure Without manipulating anything save the tool itself, and which will not interfere with the rotation of the shaft and tool in either direction, and which, at the same time, will be simple, cheap, and not at all liable to get out of order. To such end, therefore, my invention consists, first, in an improved dental tool, for use in combination with a dental engine, having a shank of lesser diameter than the portion of the body nearest to it, and also having a lug projecting outward from this -reduced shank, preferably ilush with the aforesaid adjacent portion ofthe body. My invention consists, secondly, in the combination with an enveloping sleeve or hand-piece and a rotary shaft, the terminal portion of which shaft is provided with a socket in its end and with a slot and shoulders, and, preferably, with an intern all y-arran ged spiral or other spring, whereby it is adapted to receive the shank of the ft'ool and interlock with the lug or projection on said shank by simply turning it to the right or left when seated in the socket, and thereby` be securely and firmly held without any liability of becoming accidentally disengaged.

In the accompanying drawing, Figure l is a longitudinal section of the hand-piece and a portion of the exible shaft of a dental engine, showing my invention applied thereto. Fig. 2 is anvenlarged side view of the end portion of said shaft, showing the socket for receiving the shank of the tool. Fig. 3 is also a correspondently-enlarged side View of a tool of my improved construction. Fig. 4 is an enlarged cross-section taken on the plane of the line a' w, in Fig. l. Fig. 5 is a transverse section through the socket taken on the plane of the line y y in Fig. 2; and Fig. 6 is a longitudinal section of the socket taken on the plane of the dotted line z z in Fig. 2.

Similar letters of reference indicate corresponding parts in all of the figures.

.A C designate a portion of the rotary shaft of a dental engine, and'B a flexible section of suoli shaft. I have shown that portionof the shaft lettered A C as made in two parts, the part@ being provided with a squared tongue at its--rear end which fits into a corresponding socket in the forward end of the part A, and these two parts are practically one shaft so far as the rotation of the same is concerned. I Gr designates the sleeve, which is also made iu two parts, the part G screwing upon the part I at or near the joint A of the shaft A C, and a thumb-nut, J, is employed to secure the two parts more firmly together, after the fashion of the union coupling. Of course it will be understood that the shaft A C may be in one piece, as usually constructed, and may be provided with a collar, d, which serves as its bearing or `journal portion inside the sleeve, and that the sleeve I Gr may also be in one piece. The socket p, which receives the burrdrill or other dental tool, is made in the outer end of the rotary shaft A G, and will be presently fully described. D designates the tool constructed according to my invention. rIhe particular kind of tool shown is a burr,77 so called, but,inasmuch as my present invention has no particular reference to the operating end of the tool, it will be understood that this end of the tool may be of the usual construction, according to the purpose for which it is designed to be used in a dental engine. rIhe rear end of the tool is turned or cut down so as to form a shank, c, of lesser diameter than the portion of the body nearest to it, and this shank c is provided with a lug or projection, c, which may be left standing when forming the shank, or may be a separate piece affixed thereto. I prefer to have this lug or projection rectangular, or nearly so, and I also prefer that its length shall be such as not to carry it beyond the circumference of the body portion of the tool. The mouth of the socket p, for a certain distance, is preferably made just large enough to receive the body portion of the tool D adjacent to its shank e, whereby the tool is held steadily; and the said socket j is preferably contracted j ust behind this mouth to a diameter just suiiicient to receive the shank of the tool; and the wall of this contracted portion is grooved or entirely cu-t out, as shown by the slot z', (see Fig. 2,) so as to form a passage-way, through which the projection c on the tool may pass on its way to the said cut-away portion or slot s. This slot s,

it will be observed, is cut transversely across the socket p and in such manner as to leave a shoulder, s', on each side of the slot or pas A spiral or other suitable spring,

sage-way z'.

(See

g, is placed in the rear end of the socket. Fig. 6.)

projection, c, enters the mouth of the socket. It is then turned with the thumb or finger till the said projection finds its passage-way, z', when said tool is lpushed in against the resistance of the spring g sufficiently far to throw the projection c behind one of the shoulders s', where it will be retained securely in position so long as the shaft A C revolves in one direction, and, if it be desired to revolve the .so that no forward or backward motion can occur to interfere with a proper operation of the same. Of course it is obvious that, if my improvement is designed for use with a dental engine, the shaft of which rotates in one direction only, the slot s would only need to be made on one side of the passage-way t'.

That I claim as my invention, and desire to secure by Letters Patent, is-

l. A dri-ll, burr, or tool, D, provided with a shank, c, of lesser diameter than that portion of the tool adjacent to it, and said shank being provided with a radial lug or projection, c, and the whole tool being constructed and adapted for use, in combination with the handpiece of a dental engine, substantially as hereinafter specified.

2. The combination with the enveloping sleeve of the hand-piece of a dental engine of a rotary shaft, the extreme end of which is provided with the socket p i s, substantially as herein specified. v

3. rIhe combination of a spiral or other suit able spring, g, with the said tool-socket, substantially as herein specified.

4. The combination of the drill, burr, or tool D, e, c, with the rotary shaft A G, provided with the said socket, and enveloped wholly or partially by a sleeve, substantially as herein specied.

JAMES B. MORRISON.

Vitnesses WILLIAM JorrNsroN, Trino. E. GREEN.

To fasten the tool in its socket its shank is inserted through the sleeve until its 

